There are several related developments of the Su-27 design. The Su-30 is a two-seat, dual-role fighter for all-weather, air-to-air and air-to-surface deep interdiction missions. The Su-33 'Flanker-D' is a navy fleet defense interceptor for use on aircraft carriers. Further versions include the side-by-side 2-seat Su-34 'Fullback' strike variant and the Su-35 'Flanker-E' improved air defense fighter.

In 1969, the Soviet Union learned of the U.S. Air Force's "F-X" program, which resulted in the F-15 Eagle. The Soviet leadership soon realized that the new American fighter would represent a serious technological advantage over existing Soviet fighters. What was needed was a better-balanced fighter with both good agility and sophisticated systems. In response, the Soviet General Staff issued a requirement for a Perspektivnyy Frontovoy Istrebitel (PFI, literally "Prospective Frontline Fighter", roughly "Advanced Frontline Fighter").[2] Specifications were extremely ambitious, calling for long range, good short-field performance (including the ability to use austere runways), excellent agility, Mach 2+ speed, and heavy armament. The aerodynamic design for the new aircraft was largely carried out by TsAGI in collaboration with the Sukhoi design bureau.[2]

When the specification proved too challenging and costly for a single aircraft in the number needed, the PFI specification was split into two: the LPFI (Lyogkyi PFI, Lightweight PFI) and the TPFI (Tyazholyi PFI, Heavy PFI). The LPFI program resulted in the Mikoyan MiG-29, a relatively short-range tactical fighter, while the TPFI program was assigned to Sukhoi OKB, which eventually produced the Su-27 and its various derivatives.

Soviet Su-27 in-flight

The Sukhoi design, which was altered progressively to reflect Soviet awareness of the F-15's specifications, emerged as the T-10 (Sukhoi's 10th design), which first flew on 20 May 1977. The aircraft had a large wing, clipped, with two separate podded engines and a twin tail. The ‘tunnel’ between the two engines, as on the F-14 Tomcat, acts both as an additional lifting surface and hides armament from radar.

The T-10 was spotted by Western observers and assigned the NATO reporting name 'Flanker-A'. The development of the T-10 was marked by considerable problems, leading to a fatal crash of the second prototype, the T-10-2 on 7 May 1978 due to shortcomings in the FBW control system. Extensive redesigns followed (T-10-3 through T-10-15) and a revised version of the T-10-7, now designated the T-10S, made its first flight on 20 April 1981. It also crashed due to control problems and was replaced by T-10-12 which became T-10S-2. This one also crashed on 23 December 1981 during a high speed test killing the pilot.[3][4] Eventually the T-10-15 demonstrator, T-10S-3, evolved into the definitive Su-27 configuration.[5]

The T-10S-3 was modified and officially designated the P-42, setting a number of world records for time-to-height, beating those set in 1975 by a similarly modified F-15 called "The Streak Eagle".[6] The P-42 "Streak Flanker" was stripped of all armament, radar and operational equipment. The fin tips, tail-boom and the wingtip launch rails were also removed. The composite radome was replaced by a lighter metal version. The aircraft was stripped of paint, polished and all drag-producing gaps and joints were sealed. The engines were modified to deliver an increase in thrust of 2,204 lb (1,000 kg), resulting in a thrust-to-weight ratio of almost 2:1 (for comparison with standard example see Specifications).[7][8]

The production Su-27 (sometimes Su-27S, NATO designation 'Flanker-B') began to enter VVS operational service in 1985, although manufacturing difficulties kept it from appearing in strength until 1990.[9] The Su-27 served with both the V-PVO and Frontal Aviation. Operational conversion of units to the type occurred using the Su-27UB (Russian for "Uchebno Boevoy" - "Combat Trainer", NATO designation 'Flanker-C') twin seat trainer, with the pilots seated in tandem.[10]

When the naval Flanker trainer was being conceived the Soviet Air Force was evaluating a replacement for the Su-24 "Fencer" strike aircraft, and it became evident to Soviet planners at the time that a replacement for the Su-24 would need to be capable of surviving engagements with the new American F-15 and F-16. The Sukhoi bureau concentrated on adaptations of the standard Su-27UB tandem seat trainer. However the Soviet Air Force favoured the crew station (side-by-side seating) approach used in the Su-24 as it worked better for the high workload and potentially long endurance strike roles. Therefore the conceptual naval side-by-side seated trainer was used as the basis for development of the Su-27IB (Russian for "Istrebityel Bombardirovshchik" - "Fighter Bomber") as an Su-24 replacement in 1983. The first production airframe was flown in early 1994 and renamed the Su-34 (NATO reporting name 'Fullback').[11]

Development of a version for the Soviet Navy called the Su-27K (Russian for "Korabyelny" - "Shipborne", NATO designation 'Flanker-D') commenced not long after the development of the main land based type. Some of the T10 demonstrators were modified to test features of navalized variants for carrier operations. These modified demonstrators led to specific prototypes for the Soviet Navy, designated "T10K" (Korabyelny). The T10Ks had canards, an arresting hook and carrier landing avionics as well as a retractable inflight re-fueling probe. They did not have the landing gear required for carrier landings or folding wings. The first T10K flew in August 1987 flown by the famous Soviet test pilot Viktor Pugachev (who first demonstrated the cobra manoeuvre using an Su-27 in 1989), performing test take-offs from a land-based ski-jump carrier deck on the Black Sea coast at Saky in the Ukrainian SSR. The aircraft was lost in an accident in 1988.

At the time the naval Flanker was being developed the Soviets were building their first generation of aircraft carriers and had no experience with steam catapults and did not want to delay the introduction of the carriers. Thus it was decided to use a take-off method that did not require catapults by building up full thrust against a blast deflector until the aircraft sheared restraints holding it down to the deck. The fighter would then accelerate up the deck onto a ski jump and become airborne.[12]

The production Su-27K featured the required strengthened landing gear with a two-wheel nose gear assembly, folding stabilators and wings, outer ailerons that extended further with inner double slotted flaps and enlarged leading-edge slats for low-speed carrier approaches, modified LERX (Leading Edge Root eXtension) with canards, a modified ejection seat angle, upgraded FBW, upgraded hydraulics, an arresting hook and retractable in-flight refuelling probe with a pair of deployable floodlights in the nose to illuminate the tanker at night. The Su-27K began carrier trials in November 1989, again with Pugachev at the controls, on board the first Soviet aircraft carrier, called "Tbilisi" at the time and formal carrier operations commenced in September 1991.[13][14]

Development of the naval trainer, called the Su-27KUB (Russian for "Korabyelny Uchebno-Boyevoy" - "Shipborne Trainer-Combat"), began in 1989. The aim was to produce an airframe with dual roles for the Navy and Air Force suitable for a range of other missions such as reconnaissance, aerial refuelling, maritime strike and jamming. This concept then evolved into the Su-27IB (Su-34 "Fullback") for the Soviet Air Force. The naval trainer had a revised forward fuselage to accommodate a side-by-side cockpit seating arrangement with crew access via a ladder in the nose-wheel under carriage and enlarged canards, stabilisers, fins and rudders. The wings had extra ordnance hard-points and the fold position was also moved further outboard. The inlets were fixed and did not feature FOD suppression hardware. The central fuselage was strengthened to accommodate 45 tonnes (99,000 pounds) maximum gross weight and internal volume was increased by 30%. This first prototype, the T-10V-1, flew in April 1990 conducting aerial refuelling trials and simulated carrier landing approaches on the Tbilisi. The second prototype, the T-10V-2 was built in 1993 and had enlarged internal fuel tanks, enlarged spine, lengthened tail and tandem dual wheel main undercarriage.[11]

In 1991, the production facilities at Komsomolsk-on-Amur and Irkutsk developed export variants of the Su-27: the Su-27SK single seat fighter and Su-27UBK twin-seat trainer, (the K in both variants is Russian for "Kommercheskiy" - literally "Commercial")[15] which have been exported to China, Vietnam, Ethiopia and Indonesia.[16]

Since 1998 the export Su-27SK has been produced as the Shenyang J-11 in China under licence. The first licensed-production plane, assembled in Shenyang from Russian supplied kits, was flight tested on 16 December 1998. These licence-built versions, which numbered 100, were designated J-11A. The next model, the J-11B made extensive use of Chinese developed systems within the Su-27SK airframe.[17]

Starting in 2004, the Russian Air Force began a major update of the original Soviet Su-27 ('Flanker-B') fleet. The upgraded variants were designated Su-27SM (Russian for "Seriyniy Modernizovanniy" - literally "Serial Modernized"). This included upgrades in air-to-air capability with the RVV-AE missile with an active radar homing head. The modernized Su-27SM fighters belong to the 4+ generation. The strike capability was enhanced with the addition of the Kh-29T/TE/L and Kh-31P/Kh-31AASM and KAB-500KR/KAB-1500KR smart bombs. The avionics were also upgraded.[18]

The Su-30 is a two-seat multi-role version developed from the Su-27UBK and was designed for export and evolved into two main variants. The export variant for China, the SU-30MKK ('Flanker-G') which first flew in 1999. The other variant developed as the export version for India, the Su-30MKI ('Flanker-H') was delivered in 2002 and has at least five other configurations.

The Su-33 is the Russian Navy version of the Soviet Su-27K which was re-designated by the Sukhoi Design Bureau after 1991. (Both have the NATO designation 'Flanker-D')

The Su-34 is the Russian derivative of the Soviet-era Su-27IB, which evolved from the Soviet Navy Su-27KUB operational conversion trainer. It was previously referred to as the Su-32MF.

The newest and most advanced version of the Su-27, as of 2014, is the Su-35S ("Serial"). It was previously referred to as the Su-27M, Su- 27SM2 and Su-35BM.[19]

The Su-37 is an advanced technology demonstrator derived from Su-35 prototypes, featuring thrust vectoring nozzles made of titanium rather than steel and an updated airframe containing a high proportion of carbon-fibre and Al-Li alloy.[20] Only two examples were built and in 2002 one crashed, effectively ending the program. The Su-37 improvements did however make it into new Flanker variants such as the Su-35S and the Su-30MKI.[21]

This section requires expansion with: Development of later Su-27 versions and upgrades should be covered here also.. (August 2014)

The Su-27 had the Soviet Union's first operational fly-by-wire control system, based on the Sukhoi OKB's experience with the T-4 bomber project. Combined with relatively low wing loading and powerful basic flight controls, it makes for an exceptionally agile aircraft, controllable even at very low speeds and high angle of attack. In airshows the aircraft has demonstrated its maneuverability with a Cobra (Pugachev’s Cobra) or dynamic deceleration – briefly sustained level flight at a 120° angle of attack.

Su-27 carrying R-27 missiles

The naval version of the 'Flanker', the Su-27K (or Su-33), incorporates canards for additional lift, reducing takeoff distances. These canards have also been incorporated in some Su-30s, the Su-35, and the Su-37.

The Su-27 is armed with a single 30 mm Gryazev-Shipunov GSh-30-1 cannon in the starboard wingroot, and has up to 10 hardpoints for missiles and other weapons. Its standard missile armament for air-to-air combat is a mixture of R-73 (AA-11 Archer) and R-27 (AA-10 'Alamo') missiles, the latter including extended range and infrared homing models.

The Soviet Air Force began receiving Su-27s in June 1985. It officially entered service in August 1990.[23]

On 13 September 1987, a fully armed Soviet Su-27, Red 36, intercepted a Norwegian Lockheed P-3 Orion maritime patrol aircraft flying over the Barents Sea. The Soviet fighter jet performed different close passes, colliding with the reconnaissance aircraft on the third pass. The Su-27 disengaged and both aircraft landed safely at their bases.[24]

These aircraft were used by the Russian Air Force during the 1992–1993 war in Abkhazia against Georgian forces. One fighter, piloted by Major Vaclav Alexandrowich Shipko (Вацлав Александрович Шипко) was reported shot down by an S-75M Dvina on 19 March 1993 while intercepting Georgian Su-25s performing close air support. The pilot was killed.[25][26]

On 7 February 2013, two Su-27s briefly entered Japanese airspace off Rishiri Island near Hokkaido, flying south over the Sea of Japan before turning back to the north.[29] Four Mitsubishi F-2 fighters were scrambled to visually confirm the Russian planes,[30] warning them by radio to leave their airspace.[31] A photo taken by a JASDF pilot of one of the two Su-27s was released by the Japan Ministry of Defense.[32] Russia denied the incursion, saying the jets were making routine flights near the disputedKuril Islands.[29] In another encounter near Japan, in 2014 a Su-27 nearly collided with an American RC-135.[33]

Ethiopian Su-27s reportedly shot down two Eritrean MiG-29s and damaged another one[35][36] in February 1999 and destroyed another two in May 2000.[36][37] The Su-27s were also used in CAP (Combat Air Patrol) missions, suppression of air defense, and providing escort for fighters on bombing and reconnaissance missions.[38] The EtAF used their Su-27s to deadly effect, bombing Islamist garrisons and patrolling the airspace. The Su-27 has replaced the aging Mikoyan-Gurevich MiG-21, which was the main fighter of the EtAF between 1977 and 1999, as Ethiopia's main air superiority fighter.[39]

The Su-27 entered Angolan service in mid-2000 during the Angolan Civil War. It is reported that one Su-27 in the process of landing, was shot down by SA-14 MANPADs fired by UNITA forces on 19 November 2000.[35][40]

Four Indonesian Flanker-type fighters including Su-27s participated for the first time in the annual Pitch Black exercise in Australia on 27 July 2012. Arriving at Darwin, Australia the Indonesian fighters two Su-27s and two Su-30s were escorted by two Australian No. 77 Squadron F/A-18 Hornets.[41] Exercise Pitch Black is a major multi-national biennial exercise hosted by the Royal Australian Air Force, involving Offensive Counter Air and Offensive Air Support missions being flown at training ranges across the Northern Territory. Exercise Pitch Black 12 was conducted from 27 July through 17 August 2012, and involved 2,200 personnel and up to 94 aircraft from Australia, Indonesia, Singapore, Thailand, New Zealand and the United States.[42]

During the post-Euromaidan Ukrainian crisis of 2014, a Ukrainian Air Force Su-27 was scrambled to intercept Russian fighter jets that violated Ukraine's airspace twice over the Black Sea on 3 March to prevent any possible "provocative actions".[43] With no Air to Air opposition and other aircraft available for Air to Ground duties, Ukrainian Su-27s played a little role in the 2014–15 Ukraine conflict. Ukrainian Su-27s were recorded performing low fly passes and were reported flying top covers, combat air patrols and eventual escort or intercept of civil aviation traffic over Eastern Ukraine.[44][45] During one of these flights, the claim about the downing of an Ukrainian Su-27 surfaced on 15 April 2014, but the video proved to be fake, taken from a previous video of the Syrian civil war. Videos of the Su-27s involved in the operation performing low fly passes revealed they were armed with R-27 and R-73 Air to Air missiles.[46]

Su-27M (Su-35/Su-37, Flanker-E/F): Improved demonstrators for an advanced single-seat multi-role Su-27S derivative. These also included a two-seat "Su-35UB" demonstrator.

Su-27PU (Su-30): Two seat version of the Su-27P interceptor, designed to support with tactical data other single-seat Su-27P, MiG-31 and other interceptor aircraft in PVO service. Later prototypes renamed Su-30 by Russia, and modified into a multi-role fighter mainly for export market, moving away from the original purpose of the aircraft.

Su-27PD: Single-seat demonstrator with improvements such as inflight refuelling probe.

Su-30M / Su-30MK: Next-generation multi-role two-seater. A few Su-30Ms were built for Russian evaluation in the mid-1990s, though little came of the effort. The Su-30MK export variant was embodied as a series of two demonstrators of different levels of capability. Versions include Su-30MKA for Algeria, Su-30MKI for India, Su-30MKK for the People's Republic of China, and Su-30MKM for Malaysia.

Su-27SKM: Single-seat multi-role fighter for export. It is a derivative of the Su-27SK but includes upgrades such as advanced cockpit, more sophisticated self-defense electronic countermeasures (ECM) and an in-flight refuelling system.[49]

Su-27UBM: Comparable upgraded Su-27UB two-seater.

Su-27SM2: 4+ gen block upgrade for Russian Su-27, featuring some technology of the Su-35BM; it includes Irbis-E radar, and upgraded engines and avionics.

Su-27SM3: The same as the Su-27SM but is built new rather than a mid-life upgrade.[50]

Su-27KUB: Essentially an Su-27K carrier-based twin-seater with a side-by-side cockpit, for use as a naval carrier trainer or multi-role aircraft.

Su-35BM/Su-35S: Also named the "Last Flanker" is latest development from Sukhoi Flanker family. It features improved AL-41F1S engine, newer avionics and new radar.

People's Liberation Army Air Force (PLAAF) – 59 Su-27 fighters, consisting of 33 Su-27SKs and 26 Su-27UBKs as of January 2013[51] The Flankers were produced under three separate contracts by the Russian KnAAPO and IAPO plants. Delivery of the aircraft began in February 1991 and finished by September 2009. The first contract was for 18 Su-27SK and 6 Su-27UBK aircraft. The deal, known as '906 Project' within China, saw the Su-27 exported to a foreign country for the first time. In February 1991, an Su-27 performed a flight demonstration at Beijing's Nanyuan Airport. The official induction to service with the PLAAF occurred shortly thereafter. Chinese Su-27 pilots described its performance as "outstanding" in all aspects and flight envelopes. Differences over the payment method delayed the signing of the second, identical contract. For the first batch, 70% of the payment had been made in barter transactions with light industrial goods and food. Russian Federation argued that future transactions should be made in US dollars. In May 1995, Chinese Central Military Commission Vice Chairman, Liu Huaqing visited Russia and agreed to the term, on a condition that the production line of Su-27 be imported. The contract was signed the same year. Delivery of the final aircraft from the second batch, occurred in July 1996. In preparation for the expanding Su-27 fleet, the PLAAF sought to augment its trainer fleet. On December 3, 1999, a third contract was signed, this time for 28 Su-27UBKs. All 76 of the aircraft featured strengthened airframe and landing gear – result of the PLAAF demands that the fighter has a "usable" air-ground capability. As a result, the aircraft are capable of employing most of the conventional Air-to-Ground ordnance produced by Russia. Maximum Take-Off Weight (MTOW) increased to 33,000 kg (72,750 lb). As is common for Russian export fighters, the active jamming device was downgraded; Su-27's L005 ECM pod was replaced with the L203/L204 pod. Furthermore, there were slight avionics differences between the batches. The first batch had N001E radar, while the later aircraft had N001P radar, capable of engaging two targets at the same time. Additionally, ground radar and navigational systems were upgraded. The aircraft are not capable of deploying the R-77 "Adder" missile due to a downgraded fire control system,[54] except for the last batch of 28 Su-27UBKs.[55]

At the 2009 Farnborough Airshow, Alexander Fomin- Deputy Director of Russia's Federal Service for Military-Technical Co-operation, confirmed the existence of an all-encompasing contract and an on-going licensed production of the Su-27 variant by the Chinese. The aircraft are being produced as the Shenyang J-11.[56]

Russian Air Force – 359 Su-27 aircraft, including 225 Su-27s, 70 Su-27SMs, 12 Su-27SM3s, and 52 Su-27UBs in service as of January 2014.[59] A modernisation program began in 2004.[60][61][62] Half of the fleet has been modernized by 2012.[63] The Russian Air Force is currently receiving aircraft modernized to the SM3 standard.[64]

Two Su-27s were delivered to the United States in 1995.[57][67] Two more were bought from Ukraine in 2009 by a private company, Pride Aircraft. They were to be used for aggressor training for U.S. pilots.[68]

Belarusian Air Force inherited 23-28 Su-27s from the former 61st Fighter Aviation Regiment of the Soviet Union.[57] They had 22 in service as of December 2010.[58] Two or three Su-27 were sold to Angola in 1998. Belarus had 17 Su-27P and 4 Su-27UBM1 aircraft remaining when they were retired in December 2012.[52][69][70]

According to the U.S. FAA there are 2 privately owned Su-27s in the U.S.[72] Two Su-27s from the Ukrainian Air Force were demilitarised and sold to Pride Aircraft of Rockford, Illinois, USA. Pride Aircraft modified some of the aircraft to their own desires by remarking all cockpit controls in English and replacing much of the Russian avionics suite with Garmin, Bendix/King, and Collins avionics. The aircraft were both sold to private owners for approximately $5 million each.[73]

On 30 August 2010, the Financial Times claimed that a Western private training support company ECA Program placed a US$1.5 billion order with Belorussian state arms dealer BelTechExport for 15 unarmed Su-27s (with an option on 18 more) to organize a dissimilar air combat training school in the former NATO airbase in Keflavik, Iceland with deliveries due by the end of 2012.[74][75] A September 2010 media report by RIA Novosti questioned the existence of the agreement.[76] No further developments on such a plan have been reported by 2014, while a plan for upgrading and putting the retired Belorussian Air Force Su-27 fleet back to service was reported in February 2014.[77]

Russian Knights paying tribute to Igor Tkachenko, leader of the group who died during practice a week earlier

9 September 1990: A Soviet Su-27 crashed at the Salgareda airshow in 1990 after pulling a loop at too low of an altitude. The Lithuanian pilot, Rimas A.A. Stankevičius, and a spectator were killed.[78][79]

12 December 1995: Two Su-27s and an Su-27UB of the Russian Knights flight demonstration team crashed into terrain outside of Cam Ranh, Vietnam, killing 4 team pilots. Six Su-27s and an Ilyushin Il-76 support aircraft were returning from a Malaysian airshow. The aircraft were flying in echelons right and left of the Il-76 on their way to Cam Ranh for refueling. During the landing approach, the Il-76 passed too close to the terrain and the three right-echelon Su-27s crashed. The remaining aircraft landed safely at Cam Ranh. The cause was controlled flight into terrain; contributing factors were pilot error, mountainous terrain and poor weather.[80]

December 1998: An Ethiopian Air Force Su-27 crashed during a night-flying exercise, resulting in the pilot's death.[81]

6 January 1999: An Ethiopian Su-27, piloted by a Russian pilot, crashed while undergoing test flights. The pilot ejected safely.[81]

15 September 2005: A Russian Air Force Su-27P crashed in Lithuania after it strayed out of its air corridor while it was flying from St. Petersburg to Russia's Baltic exclave of Kaliningrad due to a mechanical failure. The Su-27 was armed with at least 4 air-to-air missiles. The pilot ejected and was taken into Lithuanian custody. The incident led to an international debate between Lithuania, Russia and NATO.[83][84]

29 July 2008: An Su-27UB crashed on a training flight in Primorye Territory, Russia. One pilot was killed, while the other survived.[85]

30 August 2009: A Belarus Air Force Su-27UBM crashed at the 2009 Radom Air Show in Poland. The Su-27 crashed after exiting a loop, possibly due to an engine failure from a bird strike. Both pilots died after opting to stay with the aircraft to steer it away from spectators.[88][89]

6 April 2011: A Russian Air Force Su-27SM crashed during a training drill near the city of Vladivostok in Russia's Far East. The pilot ejected unhurt.[90]

28 June 2012: A Russian Air Force Su-27UB crashed in Karelia, Russia. Both pilots ejected unhurt.[91]

31 March 2013: A Chinese PLA Air Force Su-27UBK crashed during a drill in Shangdong, China. Both pilots died.[92]